China is escalating tensions in the South China Sea to test how far the US supports one of its allies, military analyst says

• China has been escalating tensions with the Philippines in the South China Sea for months.
• Its intention is to test how far the US would support the Philippines, one military analyst told CNN.

China is escalating tensions in the South China Sea to test how far the US supports one of its allies in the region, according to a military expert.

China wants to see how far the US would go to protect the Philippines, according to Collin Koh, a senior fellow at the Institute of Defence and Strategic Studies at Singapore's Nanyang Technological University.

"China is deliberately escalating the situation, with a likely intention to test how far Washington would support Manila," Koh told CNN.

The statement comes as tensions have risen between China and the Philippines in the South China Sea in recent months, with regular flashpoints becoming commonplace.

Last week, the Philippines accused China of repeatedly firing flares at its aircraft over the region.

A patrol plane was threatened by flares from a Chinese island base as it conducted a "Maritime Domain Awareness Flight" in one incident last Thursday, according to a statement by the Philippines' National Task Force for the West Philippine Sea.

And in an X post on Monday, Philippine Coast Guard spokesperson Jay Tarriela said China had deployed 40 vessels to block its delivery of supplies to soldiers stationed in Sabina Shoal, a disputed island claimed by both China and the Philippines.

Rising tensions

It's not the first time China has escalated tensions with the Philippines in the region.

In June, Chinese coast guard armed with swords and knives attacked Filipino vessels in the contested waters, resulting in injuries and one soldier losing a thumb.

At the time, General Romeo Brawner, the Philippines' top military commander, said the incident "constitutes a blatant violation of international maritime law, Philippine sovereignty, and sovereign rights."

A month later, China's largest coastguard vessel dropped anchor in the Philippines' exclusive economic zone, which the latter described as an act of "intimidation."

Sari Arho Havrén, an associate fellow at the Royal United Services Institute who specializes in China's foreign relations, told BI in June that China's provocations are meant to "exhaust" neighboring countries into accepting its claims over contested waters.

Koh told CNN this week that China used this same strategy in 2012 to take over Scarborough Shoal, a disputed territory claimed by both countries.

He said that the Philippines is "trying to avoid what they call a repeat of the Scarborough Shoal."

How far could the US go to protect its ally?

Despite tensions, the US has so far avoided a direct confrontation with China.

But under a 1951 defense treaty, the US is expected to defend the Philippines should an armed attack occur on its forces.

Speaking at the 35th Annual International Military Law and Operations Conference in the Philippines this week, Adm. Samuel Paparo, head of the US Indo-Pacific Command, said that the "escort of one vessel to the other is an entirely reasonable option within our Mutual Defense Treaty."

This suggests that the US could send naval ships to escort Philippine vessels on resupply missions.

However, given Russia's invasion of Ukraine, the Israel-Hamas conflict in Gaza, and the upcoming US presidential elections, it is not in the US' interest to let itself get dragged into a conflict, Koh said.

And "the Chinese know that Manila has very limited options if they could not depend on US help," he added.